(a) Field of the Invention
The present invention relates to a method of mounting a semiconductor chip to a supporting member during the production of such a semiconductor device as an integrated circuit. More particularly, it pertains to a method which enables adjustment of the position of the semiconductor chip placed on a soldering preform, by making use of the surface tension of the melted solder which is used for securing the semiconductor chip to the supporting member.
(b) Description of the Prior Art
In the past, the soldering of a semiconductor chip onto a metallized portion within the cavity of a package has relied on the method comprising the steps of: arranging, on a metallized portion provided within the cavity of the package, a preform solder layer made of an eutetic alloy (composition: about 3% of silicon "Si", and the remainder being gold "Au") while the package is being heated on a heat block; placing a semiconductor (Si) chip on said solder layer of eutetic alloy by means of a vacuum pincette or a diecollet; and then scrubbing the semiconductor chip on said preform solder layer to facilitate good attachment of this chip to the eutetic alloy layer and to adjust the position of the semiconductor chip. In view of the fact, however, that this vacuum pincette or the diecollet is made of a hard metal to resist a high temperature, the semiconductor chip which is carried onto the solder preform and then scrubbed thereon by virtue of vacuum suction of the pincette or by being nipped by the diecollet is often subjected to injury or cracking due to the force applied by such sucking or nipping member made of a hard metal to the chip during the course of scrubbing.
Moreover, the eutetic alloy which contains only about 3% of silicon and the remainder gold is expensive due to the large content of gold, and moreover has a high melting point in the range of about 380.degree. to 400.degree. C. Such high temperature employed during the soldering step in the manufacture of a semiconductor device would give an adverse effect to the semiconductor chip, rejectably degrading the quality of the semiconductor device produced.
As an alternative method to eliminate the above-mentioned drawbacks and inconveniences of the prior art, there has been proposed a method which comprises the steps of: placing, via a solder preform, a semiconductor chip on a metallized layer formed within the cavity of a package; and then passing the resulting assembly through a heating furnace to perform soldering of the semiconductor chip to the chip-mounting metallized layer. This latter method is free from development of injury or cracking in the chip. However, in this latter method, the metallized portion within the cavity is formed to have a rectangular shape having an area substantially larger than the chip. Thus, this known method undesirably is entailed by large variance in the position where the chip is fixed in the semiconductor device manufactured, since it is difficult to effectively control the fixing position of the chip.